This invention relates generally to a wind turbine and more particularly to methods and systems for directing a current within the wind turbine.
A rotor blade of a wind turbine is provided with an outer lightning down-conductor arranged on an outer surface of the blade or an inner lightning down-conductor inside the blade. The inner lightning down-conductor is provided with a lightning receptor, which is a metallic through-going connection between the inner lightning down-conductor of the blade and the outer surface of the blade. A purpose of the receptor is to attract lightning so that a lightning current generated from lightning can be guided downwards though the lightning down-conductor mounted inside the rotor blade.
Use of electrically conductive material in components, such as a brake pad, a generator, and bearings supporting the generator, within the wind turbine entails a need for lightning protection or overvoltage protection for the components. In an event of the lightning strikes to the rotor blade, there is a risk that a path of the current will propagate through the rotor blade and into the components to damage the components. It is important to protect the components from the current because the damage can lead to major costly repairs of the components.